给水处理厂废弃铁铝泥对正磷酸盐的吸附特征

以给水处理厂废弃铁铝泥（ferric-alum residuals,FARs）为载体,探究了FARs对正磷酸盐的吸附特征.ICP、SEM和XRD测试结果表明,FARs富含铁铝元素且为无定形结构.批量平衡实验法证实,FARs对正磷酸盐的吸附较符合伪二级动力学模型.在酸性环境条件下,磷的吸附效果最好,当pH值从4.6升至7...

Characteristics of orthophosphate adsorption on ferric-alum residuals (FARs) from drinking water treatment plant

Batch tests have been used to investigate the characteristics of orthophosphate adsorption on ferric-alum residuals (FARs) from drinking water treatment plant. ICP, SEM and XRD analyses confirm that the FARs enriched in Fe and Al elements and presented amorphism structure. Orthophosphate sorption by the FARs can be described by the pseudo-second-order kinetics equation. Fine adsorption effects of the FARs were found under lower pH values, particularly a 40.13% drop of the adsorptive capacity from pH 4.6 to pH 7.6. The FARs with grain sizes of 0.6-0.9 mm had the highest adsorption capacity of orthophosphate. Experimental data could be better fitted by the isotherm models of Langmuir (R2 = 0.9736) and Freundlich (R2 = 0.9916). The maximal adsorptive capacity reached 45.45 mg x g(-1) estimated from Langmuir isotherm model. Compared with other natural and industrial materials, FARs has relatively higher adsorption capacity. Under similar testing conditions, it was found that only about 10% orthophosphate could be desorbed from the FARs. Further study demonstrated that the mean energy of orthophosphate sorption on the FARs was 13.36 kJ x mol(-1) and the deltaH0 > 0, deltaS0 > 0 and deltaG0 < 0, which indicated that orthophosphate sorption on the FARs was a spontaneously endothermic chemical reaction. It can be therefore highly valued that the FARs may be applied to phosphate removal from wastewater and surface water.